I have soil in my garden that the pH is 7.0 and need to lower the pH. If I add elemental sulfur to the soil (I already know the proper rate per square feet). Do I just apply the proper sulfur amount to the soil, use a shovel to distribute the sulfur into the top 8" of soil and leave it?

Or do I need to also water the area and then just wait for a month and retest the area?

  • Elemental Sulfur is usually dusted on and raked in in the fall, so soil bacteria have time to work on it. Commented Mar 19, 2020 at 14:37

2 Answers 2


Elemental sulfur must dissolve over a period of time in order to affect pH. If you're intending on planting blueberries this year, then you should scatter the sulfur on top of the mulch, working it into the mulch but not into the soil. You only need to do this twice a year (I usually applied sulfur in the spring and then again in late summer). After you've done this, you should use Ammonium sulfate as a drench - you'll have to apply this periodically throughout the season, but you'll only need to do this for a couple of years - until the sulfur begins leaching into the soil. You must apply sulfur twice a year, every year, as long as you're growing the blueberries.


I would add the sulfur as gypsum/calcium sulfate . Then there is no time delay while the sulfur flowers ( powder) slowly oxidize to sulfite or sulfate when they will become water soluble. Gypsum is lower cost and more available and has limited solubility so will act slowly. I would just water in gypsum as that takes the least work. I think people who recommend sulfur powder for soil pH are writers , not gardeners. I have a few pounds of sulfur powder ;The only good application for powder is as an insecticide or fungicide. When I acidified for blue berries , I used sulfuric acid (it works pretty fast), but I am not recommending that to anyone. The rabbits loved the resulting blueberries,the leaves and the twigs. I switched to currents ,they require no care and make better jelly.

  • Thanks for writing blacksmith37. The gypsum/calcium sulfate is that two products in one or two separate products? How much gypsum would I add per square feet to lower the Ph x amount? Thanks in advance
    – scarlson
    Commented Feb 17, 2020 at 18:29
  • I used elemental sulfur, which in my area is chunks of sulfur maybe 2-3mm x 1-2mm. This is common in my area. I've never heard of anyone applying sulfur powder except as a pesticide. Incidentally, gypsum is pH neutral (pthorticulture.com/en/training-center/…), so it may be cheaper just to mix the powder with sand. And yes, sulfur powder should leach into (and out of) the soil rather quickly. You may also want to check you cation exchange capacity (part of a soil test) to ensure that you don't add too much calcium to your soil.
    – Jurp
    Commented Feb 17, 2020 at 21:30
  • Gypsum is a name for calcium sulfate. A strong acid plus a weak base , an acidic material , check a Chem 101 text. S must oxidize to be soluble acidic ( to SO2 or SO3) ; S is acidic but relatively water insoluble. It would be difficult to put on too much gypsum ( except in a pot), I have put on 2 lb. /sq ft ( using free drywall = gypsum ). Commented Feb 18, 2020 at 16:20

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